Advanced optical fiber communications network

ABSTRACT

An advanced optical fiber communications network comprises a multimode optical fiber connection (one fiber or two) from a central office to an intelligent interface device in the subscriber&#39;s premises. The central office includes at least a narrowband switch and a broadband switch. The narrowband switch provides voice grade telephone service routing. The broadband switch provides routing for video services and may comprise an ATM switch, an optical switch or the like. The intelligent interface device provides a connection to the optical fiber and performs two-way wavelength division multiplexing and demultiplexing as well as any necessary signal format conversions. The network has media access control functionality and utilizes a dynamic media access control procedure. The optical fiber loop to the subscriber&#39;s premises has the capacity to carry at least three different wavelengths. Bandwidth on the optical fiber loop is dynamically allocated to individual services on demand, and the allocation of bandwidth includes wavelength selection as well as bit rate allocation.

CROSS REFERENCE TO RELATED APPLICATIONS

This application describes an invention which is related to applicants'commonly assigned U.S. patent application Ser. No. 08/656,880, filed May30, 1996.

Field of the Invention

This invention relates generally to the distribution of information andcommunications services via an optical fiber network. In particular, theinvention relates to the control of wavelength division multiplexing inoptical fiber connections of a network in order to more efficiently andcost-effectively distribute information.

Background of the Invention

The distribution of high bandwidth information, such as video, isfrequently carried out over so-called hybrid fiber/coaxial (HFC)systems. These systems generally distribute the high bandwidthinformation in one direction only. The fiber optics are connected to thehead end of the system at the information source and transport a largenumber of individual signals or channels over the majority of thedistance between the head end and the user locations. The fiber opticsusually terminate at a point relatively close to a user location orgroup of user locations and are transported over coaxial cables from thetermination point to the user location or group of user locations.

A typical video signal distribution system for distributing TV programsfrom a central location is depicted in U.S. Pat. No. 4,994,909 to Graveset al. In that system, the televsision signals are transmitted by fiberoptic connections to an interface network 30 and are transmitted bycoaxial cables from there to a number of television receivers.

Many of the HFC systems are referred to as fiber to the curb systems.See, for example, U.S. Pat. No. 5,262,883 to Pidgeon and U.S. Pat. No.5,133,079 to Ballantyne et al. Such systems typically use anoptical-to-electrical converting terminal at the curb, sometimesreferred to as an optical network unit (ONU), and deliver voice andvideo downstream to the home from the terminal using coaxial cable ortwisted copper pair technology. U.S. Pat. Nos. 5,181,106, 5,189,673 and5,303,229, commonly assigned to Alcatel Systems, discuss a networkhaving a telecommunications central office connected to remote terminalsby fiber optics with the connections to the customers over twisted pair(narrowband) and coaxial cable (broadband). POTS decoding and D/Aconversion take place at the ONU and the digital signals limited tovideo information are decoded and D/A converted at the set top in theCPE.

The installation of ONUs and other active electronic units outside thepremises (on telephone poles, electric curbside units, etc.) in fiber tothe curb systems is labor and cost intensive and exposes them toinclement weather. The installation of electronic units outside thepremises to provide conversion to wire transport also erases theadvantage of additional security provided by the extreme difficulty intapping fiber optics. Even those fiber optic systems having fiber opticdrops from the curb to the home, such as in U.S. Pat. No. 5,325,223 toBears, convert the optical signals to electrical signals at the curbunits for the purpose of multiplexing and demultiplexing.

Typical fiber to the curb systems also are not efficient from thenetwork side or the customer side in their use of bandwidth over thefiber, thus ultimately increasing the cost of the system. From thenetwork perspective, the systems do not use bandwidth in an effectiveway. They also tend to be very rigid and to follow standard NorthAmerican digital hierarchies or vendor proprietary hierarchies. Suchinterfaces also tend to be very channelized and to switch large chunksof bandwidth in a discrete type manner regardless of the customer'sactual bandwidth needs. The upstream transmission is usually restrictedto signalling messages, and the upstream transmission rate back into thenetwork from the customer is extremely bandwidth limited and is nottruly dynamic.

Any switching of signals or bandwidth typically occurs at the headendwith a point to point transmission system from the headend to the ONUlocated close to the end user. The optical fiber or fiber optic pair tothe ONU carries a very high bandwidth rate which is then subdivided intosmaller bandwidths for each one of a plurality of customer premises. Forexample, the full bandwidth on the fiber may be OC-12, and thatbandwidth may be subdivided into 8 different segments, each segmenttransporting information for one premises over coaxial cable or twistedcopper pairs to that premises. See for example, copending, commonlyassigned, patent application Ser. No. 08/413,215 filed on Mar. 28, 1995entitled "Full Service Network with Distributed Architecture".

For video and POTS, all of the switching usually occurs at the headendwith channelized transmission and access back through the activeelectronics at the ONU or elsewhere in the network. For example, in U.S.Pat. No. 5,136,411 to Paik et al, electrical service request signalsfrom subscribers are converted into optical service request signals andsent to a headend terminal. The headend terminal then selects among anumber of channels for transmission to the subscribers. In U.S. Pat. No.4,506,387 to Walter and U.S. Pat. No. 4,709,418 to Fox et al, users cansend an upstream request for a selected video program to be delivereddownstream at a high rate over fiber optics to a receiving unit at theuser's location where the video signals are then displayed. Whilechannels or video programs can be selected, there is nevertheless nodynamic relationship in the allocation of fiber optic bandwidth betweenthe headend and the customer.

From the customer side, the restricted upstream transmission preventscustomers connected to fiber to the curb systems from being able togenerate signals on the network for two-way transmission in a manneranalogous to home page providers on the Internet. It would be preferableto have a system which enables a customer to send as well as receive,for example, full motion video to and from another location and whichfacilitates transmission of the content and routing signals.

Distribution systems which utilize optical fibers for the entiretransmission path to the home are known but are generally regarded asbeing substantially more expensive and less flexible than HFC or fiberto the curb systems.

U.S. Pat. No. 4,891,694 to Way pertains to a fiber optic cabletelevision distribution system in which each customer location isconnected to a remote terminal via a dedicated optical fiber. Televisionsignals are transmitted by optical fiber to a remote terminal and intoCATV tuners. An optical fiber connects the remote terminal to thecustomer location, however the remote terminal is not the interface tothe home.

U.S. Pat. No. 5,272,556 to Faulkner et al pertains to distributing HDTVsignals from a transmitter at a head station to a number of receiverslocated at customer stations along an optical network.

U.S. Pat. No. 4,135,302 to Cutler pertains to a broadcasting system inwhich a signal path between a central station and a plurality ofsubscribers includes fiber optic transmission lines. The optical fibersextend over the whole length of the transmission paths between anelectro-optical transducer at the central station and a distributionpoint or photo-sensitive detector of each of the plurality ofsubscribers.

Although these optical fiber systems are capable of delivering a largeamount of information, they nevertheless offer little flexibility inswitching between multiple channels or services.

Some fiber optic systems utilizing wavelength division multiplexing andproviding telephone, data and video services are known in the prior art.For example, U.S. Pat. Nos. 5,121,244 and 5,175,639 to Takasaki suggesta fiber optic system having auxiliary fiber optic transmission lines foruse when upgrading to higher bandwidth services. Although the fiberoptic lines may be wavelength division multiplexed, the multiplexers anddemultiplexers at both ends merely switch the entire bandwidth output ofeach fiber optic line. There is no provision made for altering orallocating different customer bandwidths over a single fiber optic line.Takasaki, for example, suggests providing auxiliary transmission linesfor flexibility in providing high bandwidth services.

U.S. Pat. No. 5,221,983 to Wagner also discusses a fiber to the homesystem utilizing wavelength division multiplexing. A central office isconnected to a plurality of remote nodes by a fiber. Each node connectsto a subscriber premises via another fiber. The central office containswave-division multiplexing modules, and their output is connected byfibers to the remote node.

U.S. Pat. No. 4,763,317 to Lehman et al discusses a communicationnetwork structured to carry both wideband and narrowband communicationsvia optical fibers to the home. Examples of the various services thatthe network provides include telephony, audio, telemetry,packet-switched interactive data, facsimile, one-way video (TV),restricted one-way video (video-on-demand) and video conferencing.Network interface equipment at the subscribers' premises connects toremote network nodes via distribution optical fibers. Each distributionoptical fiber is wavelength-division multiplexed and carries modulated(pulse-analog, pulse-code, or differential pulse-code) wideband digitalchannels as well as a multiplexed channel comprising 32time-division-multiplexed narrowband digital channels. One of thenarrowband channels carries all signaling messages.

Each remote node in the Lehman et al system comprises a digitalspace-division switch for wideband channels, and a digital time-divisionswitch for narrowband channels. All switches are controlled by a centralnode control complex over a control bus and its extensions. Signalingmessages are transferred between the signaling-message-carryingnarrowband channels and the central node complex by a subscribersignaling subsystem, via the narrowband switch and the control bus. Thecentral node optionally includes interfaces to other communicationsystems, as well as trunk communication fiber connections ChannelInteroffice Signaling (CCIS) fiber connections to other central nodes ofthe network. The central node in FIG. 2 has fibers that transmit to theremote nodes, and the remote nodes have fiber connections to vasioussubscribers.

Lehman et al is limited in flexibility because it utilizes a predefinedstatic channelization on the loop fiber. If the service or bandwidthrequirements of a subscriber change quickly, there is no means forestablishing various connections through allocated bandwidth on thefiber(s) between the home and the central office. In particular, thereis no means provided which make it possible to dynamically allocatebandwidth on the fiber distribution loops on demand.

Completely fiber optic systems such as the one in Lehman et al havelimited or no built-in functionality for dynamic access control by thesubscriber. Thus, there is no functionality that would allow asubscriber served by a fiber optic system to, for example, request,receive and pay for only the bandwidth which he desire.

Furthermore, completely fiber optic systems are usually limited to aspecific service content such as either a fiber video system or a fiberPOTS system. There is a need for an interface which canmultiplex/demultiplex as required whatever fiber optic signal is sent,thus enabling more transparent access to different information sourceswith different bandwidth requirements.

BRIEF SUMMARY OF THE INVENTION

It is an object of the present invention to provide methods andapparatus which will overcome the problems and disadvantages of knownfiber optic networks and will meet the needs discussed above.

It is an object of the present invention to deliver many differentservices to the customer using a single fiber optic network.

It is also an object of the invention to use fiber transport from acentral office to an interface type device located within the customerpremises.

It is a further object of the present invention to deliver servicesignals over a fiber transport, using various network identifiers thattake the service signals through encoding technology such as ATM, tointelligent network interfaces at the customer premises which opticallyreceive those service signals and deliver them to electrical devices inthe customer premises.

It is also an object of the present invention to provide a fiber opticsystem having a dynamic bandwidth interface with the fiber at the pointof end use having true dynamic bandwidth for whatever service issubscribed to or for whatever customer access is required.

It is a further object of the present invention is to provide anintelligent interface inside the customer premises and to providemulti-service distribution inside the customer premises, includingdynamic distribution between or within services.

A preferred embodiment of the invention provides an optical fiberconnection (one fiber or two) from a central office to an intelligentinterface device in the subscriber's premises. The central officeincludes at least a narrowband switch and a broadband switch. Thenarrowband switch provides voice grade telephone service routing. Thebroadband switch provides routing for video services and may comprise anAsynchronous Transfer Mode (ATM) switch, an optical switch or the like.Preferably, the central office also includes a packet data switch.

At the subscriber premises, the intelligent interface device providesthe connection to the optical fiber and performs two-way multiplexingand demultiplexing as well as any necessary signal format conversions.The intelligent interface device may also provide similar two-wayoptical to electrical conversion and interfacing for ISDN, telemetry,packet data, etc. Traditional media (twisted pair, coaxial cable, etc.)may be used inside the customer premises for the delivery of the variousservices.

The intelligent interface device in the subscriber premises alsoprovides a broadband connection. The broadband link within the customerpremises may take the form of an optical network, or the on-premisesbroadband distribution may rely on wireless transmissions. Theon-premises optical network may take the form of a bus, with an opticaldrop type splitter for each terminal device (e.g., 10% dropped to theterminal device, 90% passed downstream to other devices). Alternatively,the interface may include equal division splitters to provide separatelinks serving individual terminal devices.

The intelligent interface device is thus analagous to an electricaldistribution panel, in that the interface device distributesdemultiplexed signals throughout the house. If multiple RF signals aredelivered, they are converted and modulated at the interface. In thisregard, the interface device basically performs the functionalityanalogous to an optical network unit (ONU) and/or a network interfacemodule (NIM) in a terminal, except now at a central point in the home.

The intelligent interface device preferably receives power from the ACpower grid in the subscriber's premises. Alteratively, the interfacedevice may receive power from the central office via a twisted wirepair, e.g. the old telephone loop replaced by the installation of theoptical fiber loop.

The interface may also control any alarming, power monitoring or otherutility monitoring. The interface and media access control communicationwith the central office and allow total control of the optical fiberbandwidth allocation to each service. The customer may carry out anydesired or necessary communications processing at the interface ratherthan at a settop box for a TV or VCR. For example, at the interface,conversion functions could be made to, for example, get picture inpicture, watch and tape television programs at the same time, watchtelevision and receive data, etc.

The central office includes a similar interface device connected to thesubscriber's optical loop. The interface device in the central officeprovides two-way conversion between optical and electrical signals andperform the multiplexing and demultiplexing of the signals carried onthe loop. The central office interface couples the various signals onthe loop to and from the voice grade narrowband switch, the broadbandswitch and the packet data switch, as needed.

The network has media access control functionality and utilizes adynamic media access control procedure. Bandwidth on the optical fiberloop is dynamically allocated to individual services on demand. Theoptical fiber(s) can carry three different wavelengths, and allocationof bandwidth can include wavelength selection as well as bit rateallocation.

Additional objects, advantages and novel features of the invention willbe set forth in part in the description which follows, and in part willbecome apparent to those skilled in the art upon examination of thefollowing or may be learned by practice of the invention. The objectsand advantages of the invention may be realized and attained by means ofthe instrumentalities and combinations particularly pointed out in theappended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified diagram of an illustrative embodiment of anoptical fiber-to-the-home network in accordance with the invention inwhich wavelength division multiplexed information is transmitted to acustomer premises.

FIG. 2 is a four layer stack diagram, useful in explaining the functionsperformed by the elements comprising the fiber optic network shown inFIG. 1.

FIG. 3 is a simplified block diagram of matching fiber optic interfacesused in the network shown in FIG. 1.

FIG. 4 is an illustrative block diagram of a media access controllerused in the network shown in FIG. 1.

FIG. 5 is an illustrative diagram of wavelength routing employed inanother embodiment of the invention.

FIG. 6 is an illustrative diagram of a SONET optical network that may beoptimally used with the dynamic bandwidth access procedure providing aplurality of services to the customer's premises.

FIG. 7 shows the IID 101 of the SONET network embodiment of FIG. 6 inmore detail.

FIGS. 8A, 8B and 8C show exemplary CPE interfaces for residential, smallbusiness and large business customers, respectively.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An exemplary fiber optics network having dynamic bandwidth allocationaccording to the invention is illustrated in FIG. 1. The IntelligentInterface Device (IID) 101 is one element of the customer premisesequipment (CPE) . Although illustrated simply as an optical fiber from atelecommunications central office (CO) to the CPE in FIG. 1, it shouldbe understood that the fiber optic transmission path 104 may be composedof any number of duplex fibers or any plurality of simplex fibers,including a fiber optic bundle. It should also be understood that FIG. 1is a simplified illustration of a network and that the fiber opticnetwork may be of any configuration and may be extremely complicated.

The IID 101 contains a media access controller (MAC) 102, connecteddirectly to fiber optic transmission path 104, which converts inputoptical signals from fiber optic transmission path 104 to electricalsignals and converts electrical signals to optical signals.

A similar media access controller 105 on the network side preferablyconnects to a plurality of fiber optic transmission paths, 104 to104_(N), each one of which is connected to any number of differentcustomer premises, 1 to M. In an embodiment having multiple customerpremises locations, passive optical splitters and couplers (not shown)are preferably used to optically distribute all of the signals on asingle fiber optic transmission path. Each fiber optic transmission path104 to 104_(N), is preferably full duplex with two logical paths.

The serving node, preferably a telephone central office, comprises mediaaccess controller 105 and any number and variety of switched inputsproviding communications and information signals. The network shown inFIG. 1 includes a Switched Multi-Megabit Data Services (SMDS) networkinput 106, a narrowband telephone switch 107, a broadband switch 108, anoptical switch 109, and a data packet switch 110. The media accesscontroller 105 receives four input rails, each having a differentservice through one of the switches or network connections, andselectively couples each one to a different wavelength transmitted onthe fiber optic transmission paths 104 to 104_(N).

Regardless of the network architecture or other characteristics, thetransmission path over the fiber optic medium 104 is dynamicallymanaged, and the bandwidth is dynamically allocated on a regular basis,by media access controller 105 at the network side and each one of mediaaccess controllers 102 to 102_(M) on the subscriber side. Preferably,the management and allocation of bandwidth is carried out by a controllink from one of the media access controllers 102 at the customerpremises back to the CO, and control information is provided to themedia access controllers to dynamically manage the channelization andassign bandwidth.

INTELLIGENT INTERFACE DEVICE

An important feature of the fiber optics network of the invention is theintelligent interface device (IID) 101, preferably comprising a fullduplex media access controller (MAC) 102 and one or more customerinterfaces, located at the customer premises. The IID 101 is connectedto at least one network fiber optic through MAC 102 and to any number ofdifferent media in the customer premises through appropriate customerinterfaces.

The MAC 102 contains an optical receiver which receives light from fiberoptic transmission path 104 and then converts it directly intocorresponding electrical signals. An optical transmitter convertselectrical input signals to light transmitted directly into fiber optictransmission path 104. MAC 102 and its optical receiver and transmitterare permanent components of the intelligent interface device.

The customer interfaces preferably comprise a number of respectiveservice definition modules, 103 to 103-M, such as those available fromBroadband Technologies (BBT) for use with their FLX fiber-to-the curbsystems. The modules are not permanent. Each of these modules can beindividually loaded into the IID between MAC 102 and the customerinterface, replaced, upgraded by the customer as desired, etc.Description thereof is provided in the Executive Overview of the FLXSystem, Section BBT-200-901, Planning and Engineering, Issue 2.3X,October 1992, pp. 3-28, which is hereby incorporated in its entirety byreference. The service definition may provide conventional services. Forexample, a telephone service module would comprise circuitry for all ofthe necessary BORSCHT (battery, overvoltage, ringing, supervision,coding, hybrid and test) functionality to provide normal telephone lineservice to standard customer premises telephones connected to theinterface via a twisted wire pair. An ISDN module would comprise thestructure and functions of an ISDN PC card, such as the CyberSpaceFreedom™ series of ISDN cards available from ISDN*tek.

However, the modules 103 to 103-M in the preferred embodiment of theinvention are not limited to the functions of conventional networkcommunications interfaces. They can support a number of different higherlevel functions and perform other functions such as decoding of theimage compression scheme for full motion video proposed by the MotionPicture Experts Group (MPEG), image processing, etc. For example, adigital video service module would perform the functions of a set-topbox and, in particular, a digital entertainment terminal (DET). Thearchitecture and functional details of an exemplary DET can be found incommonly assigned copending U.S. patent application Ser. No. 08/380,755filed on Jan. 31, 1995 and entitled "Digital Entertainment Terminal withChannel Mapping" or commonly assigned copending U.S. patent applicationSer. No. 08/498,265 filed on Jul. 3, 1995 and entitled "DownloadingOperating System Software through a Broadcast Channel", both of whichare hereby incorporated by reference in their entirety.

Although the service definition modules 103 to 103-M are preferred, theIID 101 can also include network interface module (NIM) and/orprocessing circuits, such as a MPEG decoder, for receiving broadcast orvideo-on-demand services. The modules also support a variety of othercommunications services, such as telemetry meter reading, energy saving,remote control, etc. The modules support a plurality of differentphysical CPE media such as ISDN, rf coaxial cable, digital coaxialcable, local fiber optics, twisted copper wire pairs. In order tofacilitate routing, the customer interfaces may include, or be connectedto, optical combining networks so that the optical signals can be busedaround the CPE analogous to electrical signals in copper wires.

The IID 101 can be provided with a number of interfaces generallydesigned according to the needs of the user. FIGS. 8A, 8B and 8C showthree different optical transceivers. FIG. 7A is for residential usesand contains a low speed SONET terminal multiplexer which takes theOC-12 two-way and provides a two-way split down to a DS1 internalinterface. Standardized service definition module cards provide an RJ-11jack for conventional telephone service, an ISDN external interface andan ATM data is made available on twisted copper wire pair forinteractive video, etc. FIG. 8B is designed for small business and isthe same as the residential transceiver in FIG. 8A except with theaddition of a high capacity DS-3 output that segregates it in one ormore high cap services. FIG. 8C is designed for large business and wouldhave a high capacity OC-3C optical interface and an SMDS interface.These interfaces can go into a Private Branch Exchange (PBX).

The logical functions of the IID can best be understood by reference tothe four layer diagram shown in FIG. 2. The layers 1-4 in FIG. 2 are notactual elements or functions. Bottom layer 1 in FIG. 2 is the physicallayer and is comprised of the medium and the terminating connectors forthe medium, for example, a twisted copper telephone wire pair andassociated RJ-11 jacks. The MAC described above is a level 1 device, itconverts the optical signals into electrical signals and vice versa.

The next layer, layer 2, is referred to as the data link layer and isthe logic that directly controls the physical layer and is comprised of,for example, the input electrical control signals for the opticaltransmitter, either digital or analog. This layer performs thewavelength multiplexing and demultiplexing functions of IID 101 byselectively controlling the optical transmitter and receiver of the MAC102.

The next higher layer, network protocol layer 3, accomplishes thesignalling, switching and connection of services to create the network.Although shown as a single layer in FIG. 3, it is the most complicatedof the layers and may be composed of several sub-layers. It includes,for example, communications protocols and discrete switch layers fordisparate services such as Ethernet Local Area Network (LAN), FM,Switched Mega-bit Data Services (SMDS), frame relay, etc. It alsoincludes Level 1 gateways for interactive video and SS7 networks forsetting up connections across virtual switches for narrowband services.

Layer 4 rides on top of all of these other layer and constitutes theactual data being communicated from one party to another on the network.The payload, such as a video signal, can exist and remains the same indifferent network set-ups corresponding to layer 3 (ATM or SONET),different physical links comprising layer 2 (wavelength divisionmultiplexing or time division multiplexing), and different physicalmedium in layer 1 (either fiber optic, electrical wire, wirelesstransmission, etc.).

Layers 1-4 represent different levels of complexity in which there canbe alternative implementations. For example, video can be transportedover either coaxial cable or fiber optics (different physical layer).The signals can be wavelength division multiplexed or time divisionmultiplexed on the physical medium. The multiplexing can occur in an ATMnetwork or a SONET network.

In large fiber optic networks, most of the expense occurs whenincreasing the maximum bandwidth of the equipment and installationcorresponding to physical layer 1. Cost effective advantages can beachieved by effectively using the bandwidth through optimum developmentof the equipment, protocols and programmed logic corresponding to layers2 and 3, in particular, the switching of different bandwidth servicesand services operating differently at the upper level, network level 3.Current fiber optic systems typically handle level 3 operations by anumber of discrete switches, each corresponding to a respective servicesuch as Ethernet LAN, FM, SMDS, frame relay, etc., which are locatedexclusively in the central office. Such level 3 operations are handledor controlled, at least in part, by switches and other equipment withinthe intelligent interface device of the preferred embodiments.

Media access controller 102 of IID 101 shown in the preferred embodimentof FIG. 1 contains an interface between physical layer 1 and the higherlayers and carries out level 1 functions. It channels optical andelectrical signals of varying bit rates and formats to and from thephysical medium.

The downstream optical signals can be broken down into individualelectrical bits, frames or packets, which are output to be decoded inlevel 3 by the service definition modules 103 to 103-M of the IID 101,and then delivered to the electrical devices in the CPE and converted tophysical layer 4 output. For example, the optical signals can representMPEG encoded video, which then can be converted to electrical signalsand decoded by an MPEG decoder into a baseband video signal in a servicedefinition module and then delivered to a television set and convertedto a displayed image.

In the preferred embodiment shown in FIG. 1, fiber optic transmissionpath 104 is preferably a single multi-fiber optical pipe and mediaaccess controllers 102 and 105 carry out wavelength divisionmultiplexing and time division multiplexing of the signals transportedon the pipe. Spatial division is also carried out by passively splittingthe different fibers of the pipe and terminating them at differentcustomer premises.

The wavelength division multiplexing is carried out to the maximumextent safely permitted by the physical properties of the fiber optics.Presently available equipment is capable of effectively operating inthree separate wavelength regions: 850 nm, 1300 nm, and 1550 nm. Eachwavelength region can support many separate discrete wavelengths. Forexample, in the 1300 nm region, there is a 1290 nm wavelength signal, a1300 nm wavelength signal and a 1310 nm wavelength signal. Theincrements of permissible wavelength divisions and the amount of loss ordispersion vary in the different wavelength regions. For example, the1550 nm region has the lowest loss, but the 1300 nm region has the bestdispersion characteristics.

Of course, there may be more than the three specific wavelength regionsmentioned above, and each wavelength region may have wavelengthdivisions controlled down to the 10ths or hundreds or thousands ofAngstroms. In such a case, a larger number of wavelength multiplexedsignals are available for simultaneous use.

FIG. 4 shows a preferred embodiment of media access controller 105. Aseparate laser is used for each wavelength. The lasers can each be onseparate semiconductor chips, but the optical transmitter in thepreferred embodiment is comprised of a single integrated (IC) chip 401.The IC 401 has an array of 4, 8 or 16 lasers, each one of which producespulses at a different wavelength within a common wavelength region. Thelasers are not variable or tunable, but the transmitting wavelength(s)are selectable.

The illustration of the laser array constituting the optical transmitterin FIG. 4 is functional. The physical light pulses produced by thelasers on IC 401 are actually coupled by integrated optics and supplieddirectly into a single fiber 402 so that the light is already wavedivision multiplexed when it is input into the fiber. The bandwidth ofthe combined output of the four lasers is in the 10-50 Gb/ps range usingpresently available commercial equipment. If even more bandwidth ormultiplexing is necessary, two laser array ICs may be used with anoptical combiner/coupler to feed the output of both into one opticalfiber.

All of the lasers operating in a single wavelength region are preferablymade from a common substrate (for example, indium phosphate for lasersin the 1300 nm wavelength region) so that the relative difference inwavelength between the lasers is very stable. For example, if there isan increase in temperature of an IC which causes the wavelength of a1300 nm laser to increase to 1304 nm, the output of a 1310 nm wavelengthlaser on the same chip will similarly increase to approximately 1314 nm.Therefore, the difference between the output wavelengths will stayapproximately constant at 10 nm and will not decrease to 6 nm. Thewavelengths consequently always have guardbands to preventintermodulation.

The semiconductor lasers operating at discrete wavelengths withindifferent wavelength regions are fabricated on different semiconductorchips, each chip corresponding to one of the wavelength regions. Theoutputs of each chip are then combined in an optical combiner/coupleronto the fiber. However, if fabrication technologies develop to thepoint where lasers operating at wavelengths of different wavelengthregions can be placed on the same substrate, then a single chip can beused.

The optical receiver 403 has to be able to selectively receive anddetect each one of the wavelengths on fiber optic 104. Receiver 403could be controlled so that the light from fiber optic 104 goes to adetector that is only sensitive to the desired wavelength. However, itis preferable for optical receiver 403 to receive all of the differentwavelengths on the fiber 104, selectably and optically split thewavelengths and send each wavelength to a separate detector inwavelength dependent splitter 404. Each one of the separate detectors isgenerally comprised of a broadband detector, such as an avalanche diode,which has a relatively flat sensitivity response for all of thewavelengths on fiber 104.

The IID 101 interacts with the central office in a dynamic media accesscontrol procedure to decide the allocation of wavelengths and bandwidthsto customers for each call or service at required bit rates. Inparticular, the dynamic bandwidth assignment can be carried outintra-session at the customer's request. For example, when a customer onhis or her computer connected to an information service through thenetwork desires to transmit or receive a large amount of large bandwidthdata such as video, he can request that the bandwidth to his premises besubstantially increased. If the customer has an optical customerinterface on his or her IID and an optical card in the computer, thebandwidth can be increased up to the bandwidth of the fiber coming intothe premises.

When bandwidth allocation is employed using wavelength divisionmultiplexing (WDM), a large bandwidth, completely fiber optic systembecomes much more economically feasible. The physical interfacesnecessary for fiber optic transmission of 2 gigabits per second (2Gb/s)over a single wavelength (optical transmitter, fiber optic and opticalreceiver) are very expensive. It is cheaper to use, for example, foursets of 500 Mb/s interface equipment for four separate wavelengths onthe fiber.

In addition to generating and reproducing light in different wavelengthbands as described above, the media access controllers 102 and 105 alsocontrollably perform the modulation and demodulation of the light on aselectable basis. They carry out coherent transmission and subcarriermodulation of the fiber, with ample consideration given in order toprevent beats from occuring between wavelengths. The use of Nwavelengths in an optical fiber generally multiplies the bandwidth ofthe fiber by a factor of N. The number N which is practically obtainableis restricted by the physical properties of either the transmitter, thefiber optic or the receiver. The number may increase with improvementsin one or all of these elements, but the distinguishing characteristicsof this invention will remain for all values of N.

Distribution of Optical Signals to Interface

Because of the cost associated with the physical transceivers necessaryto convert the optical signals of very high bandwidths to electricalsignals and vice versa, wavelength division multiplexing creates acheaper transmission path for distribution than time divisionmultiplexing in fiber optic networks. The large savings achieved at thephysical layer, layer 1 in FIG. 3, more than compensates for thecomplexity introduced into layers 2 and 3. The different wavelengths maybe used for different services or for different customer premises.Separation of wavelengths for each customer provides security in thedistribution of information because one customer premises does notreceive the information selectively distributed to another customerpremises.

A preferred embodiment for distribution (separation and routing) of thewavelength multiplexed signals is illustrated in FIG. 5. The opticaltransmitter 401 of MAC 105 is connected to the optical receiver in eachone of a plurality of customer premises and transmits and receives, fullduplex, a multiple number (n) of different wavelengths. A passivewavelength dependent splitter 501 receives the fiber optic signals fromthe optical tranmitter 401 and separates the transmitted optical signalsby wavelength into two legs, thereby demultiplexing the wavelengthdivision multiplexed optical signals according to wavelength. Each legis input to another wavelength dependent splitter 502 which splits theleg into two wavelengths.

Each one of the separated wavelengths is forwarded to a correspondingCPE wherein it is received by one of the MAC's 1021 to 1024. Thestructure of the MAC's do not need to change in this distributionembodiment. The optical receiver is controlled to be responsive to theseparated wavelength and the laser in the transmitter array whichcorresponds to the separated wavelength is selected and controlled fortransmitting optical signals to MAC 105. Mulitplexing and demultiplexingno longer must be carried out by IID 101.

Sonet Network

A synchronous optical network (SONET), connected to the CPE according tothe present invention and utilizing the intelligent interface device ofFIG. 4, is shown in FIG. 6. The basic module or first level of theSynchronous Optical Network (SONET) signal is called the SynchronousTransport Signal-Level 1 (STS-1). The STS-1 has a bit rate of 51.84Mb/sec and is synchronous. The STS-1 signal is formed from a sequence ofrepeating frames. The STS-1 frame is illustrated in FIG. 2 of U.S. Pat.No. 5,293,376. The STS-1 frame structure can be drawn as 90 columns by 9rows of 8-bit bytes. The order of transmission of the bytes is row byrow, from left to right across the columns, with one entire frame beingtransmitted every 125 micro-seconds. The 125 micro-second frame periodsupports digital voice signal transport encoded using 1 byte/125micro-seconds=64 kb/s. The first three columns of the STS-1 framecontain section and line overhead bytes. The remaining 87 columns formthe STS-1 Synchronous Payload Envelope (SPE) . The SPE carries SONETpayloads including 9 bytes of path overhead. The STS-1 can carry a clearchannel DS3 signal (44.736 Mb/s) or, alternatively, a plurality oflower-rate signals such as DS0, DS1, DS1C, and DS2 by dividing theSynchronous Payload Envelope into a plurality of fixed time slots. Forexample, 648 DS0 signals fit into the SPE of an STS-1 signal.

Higher rate SONET signals are obtained by byte interleaving N framealigned STS-1 signals to form an STS-N signal in accordance withconventional SONET technology. An STS-N signal may be viewed as having arepetitive frame structure, wherein each frame comprises the overheadbits of N STS-1 frames and N synchronous payload envelopes. For example,three STS-1 signals may be multiplexed by a multiplexer into an STS-3signal. The bit rate of the STS-3 signal is three times the bit rate ofan STS-1 signal and the structure of each frame of the STS-3 signalcomprises three synchronous payload envelopes and three fields ofoverhead bits from the three original STS-1 signals. When transmittedusing optical fibers, the STS-N signal is converted to optical form andis designated as the OC-N signal. A more detailed description of SONETappears in U.S. Pat. No. 5,293,376.

The SONET network of FIG. 6 preferably comprises a plurality of fiberoptic hubs 601₁, 601₂, to 601_(N) on the SONET network side of the fiberoptic medium of ring 602. Each fiber optic hub can drop and add opticalsignals to and from the SONET ring 602. The SONET ring 602 may receivesignals from a variety of input sources and distributes those signalsthrough the media access controllers 105₁ to 105_(N). In particular, theSONET network contains a SONET gateway multiplexer 603 having aplurality of network interface cards 604 for receiving a variety ofinputs. For example, a narrowband switch 605 provides narrowbandtelephone communications from telephone network 606. An ATM switch 607,connected to SONET gateway multiplexer 603, couples ATM signals to andfrom ATM switch 607 on the SONET ring 602. The ATM switch 607 may bethat disclosed in copending, commonly assigned, patent application Ser.No. 08/413,215 filed on Mar. 28, 1995 entitled "Full Service Networkwith Distributed Architecture", which is hereby incorporated byreference in its entirety.

These inputs to the gateway 603 preferably include narrowband transportfor voice and narrowband data services. A digital switch or an analogimplementation of a Service Switching Point (SSP) switch 605 providesstandard type plain old telephone service (POTS) for telephone customers606. The digital POTS switch provides a DS1 type digital input/outputport through interfaces conforming to either TR008 or TR303. The DS1goes directly to a SONET gateway multiplexer 603. The multiplexer mayalso receive telephone signals in DS1 format from an analog switchthrough a central office terminal. The central office terminal convertsanalog signals to digital and digital signals to analog as necessary toallow communication between the analog switch and the rest of thenetwork.

The signals are made available at one of the SONET drop/add hubs 601 andwavelength multiplexed by the corresponding MAC 105 (possibly timedivision multiplexed with a number of DS1 signals) for transmission overone wavelength on the fiber optic transmission path 104 to IID's 101.

A preferred embodiment of the IID 101 for use in the SONET network ofFIG. 6 is shown in FIG. 7. Each IID 101 preferably contains an opticalinterface 701 for two-way conversion, a SONET terminal multiplexer 702,and a plurality of service definition module cards 703₁ to 703_(M). TheSONET terminal multiplexer 702 preferably provides telephony service andcomplies with TA-TSY-000303, IDLC System Generic Requirements,Objectives and Interface: Feature Set C--SONET interface (Supplement 2); Bellcore, Issue 3, December 1987, hereby incorporated by reference.The standard protocol for MUX 702 to signal with SONET drop/add fiberhubs 601₁ to 601_(N) and the functionality of MUX 702 are defined inTA-TSY-000253, SONET Transport Systems: Common Generic Criteria;Bellcore, Issue 5, February 1990. One of the service definition modulecards provides ATM cells as output with STS-1 interface on twisted pairto an ATM Packet Assembler/Disassembler (PAD) 704 and a terminal device705.

ATM switch 607 receives and outputs broadcast video signals 609 and/orvideo signals from a Level 2 Gateway 610 under the control of Level 1Gateway 608. The ATM switch 607 uses known encoding technology toprovide various network identifiers that take the service signalsthrough the fiber optic network to corresponding broadband electricaldevices at the customer premises. The Intelligent Interface Devices 101which optically receive those service signals, convert them toelectrical signals and deliver them to electrical devices in thecustomer premises.

Of course, the broadband SONET network shown in FIG. 6 may have anynumber of connected sources and end users and may deliver any type of,or any number of types of, broadband information. For example, it couldalso transmit digital multimedia information and the customer premisesequipment could include a personal computer and computer monitor insteadof, or in addition to, a DET and television. The broadband informationis made available at one of the SONET drop/add hubs 601 and wavelengthmultiplexed by the corresponding MAC 105 (possibly time divisionmultiplexed with a number of DS1 signals) for transmission over onewavelength fiber optic transmission path 104.

The dynamic media access control is done in three phases. As anillustrative example, consider a telephone call. A twisted pairconnection is established to the interface device when a telephone goesoff-hook. The MAC 102 in the interface 101 then negotiates with MAC 105to obtain a bandwidth path for the voice on an assigned wavelength onfiber path 104. A channel is developed on a wavelength for the signalingcommunications of the dynamic media access control procedure carried outbetween each IID 101 and a corresponding MAC 105 using either anasynchronous optical protocol, or the synchronous (SONET) OC ratetransport. The signaling information may be broadcast over all of thefiber optics couplings, 612₁ to 612_(N), to optical coupler 611 in atime division multiplexed channel. In this case, each one of the IID's101 is addressable and/or is assigned a predetermined time slot andincludes means to selectively receive and decode the signalling dataindicating the bandwidth allocation for that IID 101. The multiplexingand demulitplexing of the MAC 102 is carried out in accordance with thedecoded data obtained and stored by the IID 101.

Each IID 101 includes means to receive selection signals from a user viaremote control, direct entry or through the distribution networkinternal to the CPE. The IID responds by transmitting appropriate datasignals over a narrowband signaling wavelength channel on the fiberoptic transmission path 104 to the corresponding MAC 105. The MAC 105 isalso addressable and/or assigned a time slot for signallingcommunications. If the data represents bandwidth request, wavelengthrequest or bit rate request selection signals, the MAC 105 dynamicallyresponds to that data by allocating bandwidth, wavelengths or bit rateconnections as outlined above, and stores data identifying eachsubscriber's selections or preferences for subsequent communications.

The following execution of a narrowband telephone call is given as anexample of the dynamic bandwidth allocation procedure. When a telephoneset 111 goes off-hook a relay closes and current flows through thetelephone and twisted wire pair 112. The intelligent interface device101 recognizes this as an off-hook condition. In response, the interface101 transmits a request for dial tone upstream over fiber 104, via someestablished signaling channel and predefined signaling protocol. If thebandwidth necessary for the telephone call is available on fiber 104,the interface at the central office or corresponding MAC 105 allocates awavelength and a time slot on fiber 104 to the desired telephone calland transmits back a signaling message identifying the allocatedwavelength and time slot to the interface device 101 at the customerpremises. The interface at the central office concurrently establishes aconnection to narrowband telephone switch 107. At this point, the fiberoptic system has established a telephone grade link through from thetelephone set 111 to the narrowband telephone switch 107, and the switch107 can accept dialed digits and complete the call through the PSTN inthe normal manner. Similar procedures are used to obtain broadbandchannels and associated signaling channels on fiber 104 and establishconnections to appropriate broadband switching systems, such asbroadband switch 108, to set up sessions with video informationproviders, e.g. for video on demand type services.

Although shown in the figures and frequently referred to as a house orother location, it is to be understood throughout this application thatthe customer premises may constitute any type of premises such as aschool, an office, an apartment building, an office building, etc. TheCPE may also be comprised of a plurality of premises, separated by asmall distance such as a housing subdivision, a university campus, etc.The CO may be a telephone company central office containing otherequipment and providing other services. Although shown and referred toas a central office, the CO may comprise any serving node which isgeographically distant from the CPE.

While the foregoing has described what are considered to be preferredembodiments of the invention, it is understood that variousmodifications may be made therein and that the invention may beimplemented in various forms and embodiments, and that it may be appliedin numerous applications, only some of which have been described herein.It is intended by the following claims to claim all such modificationsand variations which fall within the true scope of the invention.

We claim:
 1. A fiber optic communications network comprising:a telecommunications central office receiving and transmitting communications and information signals; a plurality of customer premises, each one of said customer premises having:an intelligent interface device receiving and transmitting said communications and information signals and performing wavelength division multiplexing and demultiplexing of said communications and information signals, and either one terminal device performing services requiring different bandwidth allocations or a plurality of terminal devices requiring different bandwidth allocations; a fiber optic transmission path connecting said telecommunications central office to said intelligent interface device in said one customer premises, said telecommunications central office controllably transmitting optical signals corresponding to said communications and information signals to said one customer premises over said fiber optic transmission path and receiving optical signals from said one customer premises over said fiber optic transmission path; and a plurality of service definition modules in the intelligent interface device of each one of said plurality of customer premises, said service definition modules controlling said wavelength division multiplexing and demultiplexing of said communications and information signals so as to dynamically provide said different bandwidth allocations over said fiber optic transmission path connecting said telecommunications central office to said intelligent interface device in said customer premises.
 2. A fiber optics communications network as recited in claim 1, wherein said fiber optic transmission path comprises a single full duplex optical fiber.
 3. A fiber optics communications network as recited in claim 1, wherein said fiber optic transmission path comprises two simplex optical fibers.
 4. A fiber optics communications network as recited in claim 1, wherein said telecommunications central office comprises a narrowband switch providing voice grade telephone service routing and a broadband switch providing routing for broadband services.
 5. A fiber optics communications network as recited in claim 4, wherein said telecommunications central office further comprises an asynchronous transfer mode switch.
 6. A fiber optics communications network as recited in claim 5, wherein said telecommunications central office transmits optical service signals containing network identifiers over said fiber optic transmission path; andwherein said intelligent interface device receives said optical service signals, converts said optical service signals into electrical signals and delivers the electrical signals to electrical devices in the customer premises in accordance with said network identifiers.
 7. A fiber optics communications network as recited in claim 4, wherein said telecommunications central office further comprises an optical switch providing optical signals from an optical network.
 8. A fiber optics communications network as recited in claim 1, wherein said optical signals corresponding to said communications and information signals from said telecommunications central office are transmitted simultaneously on at least three different wavelengths and said intelligent interface device contains an optical receiver for receiving at least two of said three different wavelengths.
 9. A fiber optics communications network as recited in claim 1, wherein said optical signals corresponding to said communications and information signals from said telecommunications central office are transmitted simultaneously on at least three different wavelengths and said intelligent interface device performs format conversions of said optical signals corresponding to said communications and information signals from said telecommunications central office.
 10. A fiber optics communications network as recited in claim 1, wherein the network has media access control functionality and said intelligent interface device performs a dynamic media access control procedure.
 11. A fiber optics communications network as recited in claim 10, wherein said dynamic media access control procedure supplies individual services and dynamically provides said different bandwidth allocations upon demand by a customer.
 12. A fiber optics communications network as recited in claim 8, wherein said different bandwidth allocations includes the dynamic allocation of said at least two of said three different wavelengths.
 13. A fiber optics communications network as recited in claim 12, wherein said dynamic allocation of said at least two of said three different wavelengths is performed upon demand by said customer.
 14. A fiber optics communications network as recited in claim 12, wherein said dynamic media access control procedure includes the dynamic allocation of bit rate upon demand by said customer.
 15. A fiber optics communications network as recited in claim 1, wherein said network further comprises a SONET fiber optic ring connected to said telecommunications central office and receiving said communications and information signals, said SONET fiber optic ring having a plurality of drop/add fiber hubs, each one of said hubs being connected to at least one intelligent interface device.
 16. A fiber optics communications network as recited in claim 10, wherein said intelligent interface device is addressable by said telecommunications central office.
 17. A fiber optics communications network as recited in claim 10, wherein said intelligent interface device transmits a bandwidth request signal in response to user inputs.
 18. A fiber optics communications network as recited in claim 17, wherein said user inputs are received from a remote control.
 19. An intelligent optical interface device comprising:an optical transmitter and an optical receiver, connected to at least one optical fiber, for two-way conversion between optical and electrical signals; a media access controller for controlling the optical transmitter and the optical receiver so as to send and receive wavelength division multiplexed optical signals; and at least one service definition module for controlling said media access controller, wherein said at least one service definition module is responsive to signalling communications received over said optical fiber for controlling said wavelength dependent multiplexer and demultiplexer in accordance with said signalling communications.
 20. An intelligent optical interface device as recited in claim 19, wherein said optical transmitter comprises an array of lasers, each one of said lasers operating at a predetermined wavelength, and wherein said at least one service definition module selects one or more of said lasers in accordance with said signalling communications.
 21. An intelligent interface device as recited in claim 19, wherein said media access controller performs a dynamic media access control procedure in response to said signalling communications.
 22. An intelligent interface device as recited in claim 21, wherein said dynamic media access control procedure includes the dynamic allocation of individual services upon demand by said customer.
 23. An intelligent interface device as recited in claim 19, wherein said media access controller performs a dynamic media access control procedure which includes the dynamic allocation of a plurality of different wavelengths.
 24. An intelligent interface device as recited in claim 23, wherein said dynamic allocation of said plurality of different wavelengths is performed upon demand by said customer.
 25. An intelligent interface device as recited in claim 21, wherein said dynamic media access control procedure includes the dynamic allocation of bit rate upon demand by said customer.
 26. A fiber optics communications network as recited in claim 19, wherein said intelligent interface device is addressable by said telecommunications central office.
 27. A fiber optics communications network as recited in claim 19, wherein said intelligent interface device outputs a bandwidth request signal on said at least one optical fiber in response to user inputs.
 28. A fiber optics communications network as recited in claim 27, wherein said user inputs are received from a remote control. 